1. Field
The invention relates to an iron-based brazing foil and to a method for brazing two or more components.
2. Description of Related Art
Soldering is a method for joining metal or ceramic components with the aid of a molten filler material identified as solder. Depending on the processing temperature of the solder, a distinction is made between soft soldering and brazing, the processing temperature typically exceeding the liquidus temperature of the solder by 10° C. to 50° C. While soft solders are processed at temperatures below 450° C., brazing alloys are processed at temperatures above 450° C. Brazing alloys are used in applications where a high mechanical strength of the joint and/or a high mechanical strength at elevated operating temperatures are/is required.
Components made of stainless steel or of Ni and Co alloys are often joined by means of Ni—Cr-based brazing alloys. Ni—Cr-based brazing alloys are typically available as a powder produced in an atomising process or as a paste produced by mixing the atomised powder with organic binders and solvents. In addition to powders and pastes, some Ni-based brazing alloys can be produced as ductile, at least partially amorphous brazing foils by means of a rapid solidification process.
When brazing with pastes, the binders and solvents are broken down. This can result in inadequate rheological and wetting characteristics and thus in a poor joint. These problems can be avoided by using a brazing alloy in the form of a ductile foil, resulting in a more reliable brazed seam. Certain examples of Ni-based brazing alloys which can be produced as ductile foils are disclosed in DE 10 2005 039803 A1.
As raw material costs, in particular for Ni, have increased in recent years, a reduction of the Ni content of these brazing alloys is desirable. One way of achieving this is the partial replacement of Ni by Fe. Certain examples of such alloys are disclosed in WO 02/098600.